1. Field of the Invention
The present invention relates to a system for washing clothes in an automatic washer and more particularly to an apparatus and method for causing clothes or cloth items to move within the wash chamber of an automatic washer.
2. Description of the Prior Art
FIG. 1 illustrates a conventional vertical axis washer 10 having a center agitator 12 provided within a vertical axis wash basket 14 which is rotatably supported within a tub 16. The agitator 12 extends upwardly from the bottom wall of the basket 14 and typically has a height which is substantially equal to the height of the wash basket 14. In the field of automatic washing machines of this type, it has long been accepted that the most efficient clothes movement is a pattern which provides a rollover of the clothes or cloth items down the agitator barrel, then radially outward from the oscillating agitator vanes, upward along the wall of the basket. This pattern may be described as a toroidal rollover pattern. This movement is most effectively achieved in automatic washers which have dual action agitators, such as disclosed in U.S. Pat. No. 4,068,503 wherein a top auger portion is driven in a unidirectional rotary motion and a bottom portion, having flexible vanes, is driven in an oscillatory motion.
To achieve this type of toroidal rollover pattern, vertical axis washers having center agitators require a deep fill of wash liquid as the movement of clothes within the wash basket depends on fluid motion or fluid power. U.S. Pat. No. 4,068,503 and similar wash systems, at least in part, pump wash liquid within the wash basket in a toroidal rollover pattern, as shown by the flow arrows F, such that clothes within the wash basket are moved along with the flow of wash liquid. Without free fluid movement which allows for fluid pumping and the use of fluid power, these systems do not function. Accordingly, in a vertical axis washer having an agitator, effective rollover of the clothes can not be achieved when an insufficient amount of water is supplied into the wash tub. Effective rollover requires an amount of water which completely, or almost completely, submerges the clothes load such the clothes are suspended in wash liquid.
FIG. 2 illustrates a second type of vertical axis washer 20 wherein a relatively flat or low height, disk-like impeller or pulsator 22 is provided along the bottom wall of a wash basket 24 which may be rotatably supported within a tub 26. In a similar manner to vertical axis washing machines employing agitators, for automatic washing machines of this type it has long been accepted that the most efficient clothes movement is a pattern which provides a toroidal rollover of the clothes or cloth items within the wash basket. During operation of this type of washing machine, the impeller 22 is rotated or oscillated to create water flow as indicated by the flow arrows. Clothes items are washed by moving within the wash basket along with the water flow.
Just as with the vertical axis washers having center agitators, automatic washers having bottom impellers require a deep fill of wash liquid to achieve the desired toroidal rollover pattern as the movement of clothes within the wash basket depends on fluid motion or fluid power. The bottom impellers or pulsators pump wash liquid within the wash basket in a toroidal rollover pattern such that clothes within the wash basket are moved along with the flow of wash liquid. Without free fluid movement which allows for fluid pumping and the use of fluid power, these systems do not function well.
FIG. 3 illustrates the dual energy transmission path for creating cloth movement within the conventional wash systems described above. Rotational energy from a motor is transferred to a shaft which is drivingly connected to either an agitator or an impeller, depending on the vertical axis wash system used, having at least one drive surface referred to in FIG. 3 as a vane. Two paths of mechanical energy transmission occur within the washer--the vane transfers energy to the water in the wash basket and also directly transfers energy to cloth items in the wash basket. The energy transferred to the water in the wash basket results in fluid flow and fluid power being transferred to cloth items within the wash basket such that cloth movement occurs. Fluid flow also reduces the frictional engagement between the basket side walls and the cloth items thereby promoting cloth items motion. Moreover, fluid flow transfers some torque to the wash basket. The direct contact between the vane and the cloth item results in cloth motion. The cloth motion in turn leads to additional fluid motion and some torque is transferred to the wash basket.
It can be understood, therefore, that there are generally two types of vertical axis automatic washing machines--center agitator type machines and bottom impeller or pulsator type machines. Both of these types of vertical axis washers are designed for washing clothes in a deep fill of wash liquid wherein wash liquid is supplied into the wash basket to a level sufficient to completely submerge the cloth items which are loaded into the wash basket. Fluid power is a critical component in achieving effective cloth movement within these wash systems. In fact, the prior art teaches that these systems are not capable of moving clothes within a wash basket in a toroidal rollover pattern to achieve effective cleaning without free water for generating fluid power.